"There are some imminent signings that we believe will happen over the next few days.

"But we can't get the contract registered until we are cap compliant going forward - that's the rules."

Seibold confirmed Su'A was headed to the Rabbitohs but complained why the Redfern had taken their time to finally give the deal the green light despite days of speculation.

South Sydney on Friday afternoon finally put Seibold out of his misery, announcing they had signed the forward until the end of 2021 and that the forward would be available for selection in round 17.

Yet Seibold couldn't help but have a crack at Bennett over the Rabbitohs' delayed announcement.

Bennett and Su'A (AAP)

"Everyone knows where Jaydn is going so I don't have to comment on that," Seibold said on Friday.

Asked why there had been a delay about Su'A's future, Seibold said: "Ask Souths".

Seibold has come under fire for letting go Test lock Josh McGuire, Kiwi internationals Kodi Nikorima and Jordan Kahu plus ex-NSW centre James Roberts in a purge that began in the pre-season.

But Seibold defended himself, claiming Bennett had left him with a club that was not under the salary cap.

"The reality of it is that when I took over the group the club was over the salary cap leading into March 1," Seibold said.

"In previous seasons a club had until March 1 to get under the salary cap to be compliant.

"Some decisions in the pre-season were about getting under the salary cap."

There were reports of bad blood between ex-Rabbitohs mentor Seibold and Bennett following their messy coaching swap late last year.

That perception only escalated on Friday when Seibold appeared to take another shot at Bennett when he described the 12th-placed Broncos' lacklustre form.

"We need to close the gap between our best and our worst but that has been an issue for the last couple of years for the Broncos, particularly last year," Seibold said ahead of Saturday's clash with Newcastle.